Regulating circuits for monitoring and regulating the operation of a rechargeable battery are known in the prior art, in particular under the name battery management system. In this case, operation of a battery is considered to be, on the one hand, a discharging operation of a battery, that is to say in particular the use of such a battery with a corresponding electrical load, and, on the other hand, a charging operation of a battery. In known regulating circuits, the cell voltages of the battery cells are recorded in this case as measured values by a plurality of so-called cell supervising circuits (CSCs) and are transmitted to a central control unit, the so-called battery control unit (BCU), via a communication bus. Currents measured by a current sensor can also be transmitted as further measured values to the battery control unit. By evaluating the measured values, the battery control unit determines battery properties such as, inter alia, the state of charge (SOC) of individual battery cells and the ageing of individual battery cells, which is also referred to as the state of health (SOH).
In addition, in such regulating circuits, the battery control unit is allocated the task of electrically disconnecting individual battery cells or a group of battery cells from the pole connections of the battery by controlling contactors if recorded measured values indicate a safety-critical state of these battery cells. Such disconnection of battery cells is very important in order to avoid major damage both to the battery and to an electrical load supplied by the battery or a charging device of the battery. This is also important, in particular, since damaged batteries such as lithium ion batteries may also result in risks for the user of such batteries, for example risk of fire and explosion.
On account of the relevance to safety, an attempt is therefore made, by means of diagnoses, to achieve the situation in which battery parameters relevant to the safety state of a battery cell, such as the cell voltages in particular, are reliably recorded and are reliably transmitted to the battery control unit via the communication bus. In this case, there is a constant need to further improve, in particular, the transmission security of the battery parameters in order to make it possible to reliably detect safety-critical states of battery cells.
The use of further diagnostic systems or further diagnostic routines results in this case in the disadvantage that the complexity of such regulating circuits is increased, in particular at the expense of the performance of such regulating circuits. The redundancy required on account of the relevance to safety when transmitting all battery parameters recorded by the cell supervising circuits to the battery control unit via the communication bus also results in the further disadvantage that the communication bus is heavily utilized. In addition, such regulating circuits have low scalability as a further disadvantage.
Against this background, an object of the present disclosure is to improve a regulating circuit for monitoring and regulating the operation of a rechargeable battery, in particular a lithium ion battery, in particular with regard to improved performance of such a regulating circuit and with regard to improved detection of safety-critical states of the battery cells.